Method of injection molding a preform including a radially extending element

ABSTRACT

A method and apparatus for injection molding an article including a radially extending child resistant feature. Finish block halves are provided that include a pocket and that are closable together to form a neck-finish mold cavity. Mold body halves are provided that include a core portion and that are closable together to form a body mold cavity. The core portion is advanceable toward the pocket to cooperate therewith to define a cavity for forming the child resistant feature. The core portion may be integrally formed into one or more of the mold body halves, or may be separately mounted and relatively movable with respect thereto.

FIELD OF THE INVENTION

Reference is made to U.S. Ser. Nos. 10/378,434 and 10/386,192, bothassigned to the assignee of the present application, and bothincorporated herein by reference.

This invention relates generally to a method and apparatus for injectionmolding and more particularly to a method and apparatus for injectionmolding a plastic preform for subsequent blow molding into a containerhaving a cantilevered release element.

BACKGROUND OF THE INVENTION

Child resistant features are widely sought for medicine containers,poison containers, and yet undiscovered applications. One type of childresistant feature is particularly popular for rigid bottles that areinjection molded, as typified by U.S. Pat. No. 6,039,195 to Konefal etal. Konefal et al. disclose a container having an open upper end andexternal threads formed on a neck finish proximate the open upper end.Just below the threads, a deflectable release element is integrallyformed on the container. The release element extends radially outwardlyfrom the neck finish and defines an open space between the releaseelement and the neck finish. The release element ordinarily engages lugsformed in a closure member of the container to resist removal of theclosure member by a child, unless the release element is pressedradially inwardly and/or axially downwardly. The release element iseasily manufactured using a regular injection molding process.

However, many types of useful articles are produced by single stage ormulti-stage injection blow molding (IBM) process. Such articles couldbenefit from incorporation of the above-described child resistantfeatures. IBM processes typically involve thermoplastic materials, suchas high density polyethylene, polypropylene, polyethylene terephthalate,and the like. IBM apparatuses for molding such articles typicallyinclude a mold assembly having a core pin that inserts within a pair ofmold halves that are split longitudinally, and that open and closetogether in a direction that is transverse with respect to alongitudinal axis of the core pin. Accordingly, the core pin and closedmold halves cooperate to define a mold cavity that corresponds in sizeand shape to the desired size and shape of the article being molded. Asuitable thermoplastic resin is injected into the mold assembly througha gate at one end of the closed assembly to fill the mold cavity andthereby form the article.

Unfortunately, however, the release element of the above-described childresistant container is difficult to manufacture using current injectionblow molding processes and apparatuses, because the release element canbe damaged when the mold halves retract away from each other. In otherwords, the non-symmetrical and relatively complex geometry between therelease element and the container renders it impossible to quicklyextract the container from the molds without some type of damage to therelease element.

SUMMARY OF THE INVENTION

A method of injection molding an article is provided according to thepresent invention, and includes the following steps: providing finishblocks; closing the finish blocks together to form a neck-finish moldcavity; providing a plurality of mold bodies; closing the mold bodiestogether to form a body mold cavity; providing a core portion one atleast one of finish blocks and mold bodies; providing a pocket in atleast one of the finish blocks and mold bodies; and advancing the coreportion toward the pocket, whereby the core portion cooperates with thepocket to define a cavity for forming a radially extending element ofthe article. Articles produced by the method are also contemplated bythe present invention.

An apparatus for injection molding an article is provided according tothe present invention. The apparatus includes finish blocks that definea neck-finish mold cavity, and includes mold bodies that define a moldcavity. The apparatus further includes a core portion on at least one ofthe finish blocks and mold bodies, and a pocket in at least one of thefinish blocks and mold bodies. The core portion is movable toward thepocket whereby the core portion and pocket cooperate to define a cavityfor injection molding a radially extending element of the article.

Objects, features, and advantages of this invention include providing aninjection blow molding apparatus and method for injection blow moldingarticles that minimizes the possibility of damaging the article asseparable mold halves open and close with respect to one another and asarticles are removed from the mold halves. Accordingly, a widely popularchild resistant feature can now be provided on injection blow moldedarticles.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of this invention willbe apparent from the following detailed description of the preferredembodiments and best mode, appended claims, and accompanying drawings inwhich:

FIG. 1 is a front view of a child resistant container embodying thepresent invention;

FIG. 2 is a perspective view of the child resistant container of FIG. 1;

FIG. 3 is a front view of a preform for the child resistant container ofFIG. 1, embodying the present invention;

FIG. 4A is a front elevational view of an apparatus for producing thepreform of FIG. 3 that illustrates mold body halves and neck finish moldhalves being closed together, according to an embodiment of the presentinvention;

FIG. 4B is a front elevational view of the apparatus of FIG. 4A,illustrating the mold body halves being longitudinally advanced towardthe neck finish mold halves;

FIG. 4C is a front elevational view of the apparatus of FIG. 4A, furtherillustrating clamp tonnage being applied;

FIG. 5 is a partial cross-sectional view of the apparatus of FIG. 4Ctaken along line 5—5, wherein the preform of FIG. 3 is also shown asmolded in place within the apparatus;

FIG. 6 is a partially broken out top view of an apparatus for producingthe preform of FIG. 3, according to an alternative embodiment of thepresent invention; and

FIG. 7 is a front elevational view of the apparatus of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in detail to the drawings, FIGS. 1 and 2 illustrate acontainer 10 and FIG. 3 illustrates a container preform 110. Thecontainer preform 110 is injection molded and the body 112 thereofsubsequently blow molded to form the container 10 with an expanded body12.

The container 10 and preform 110 are composed of polymeric material,such as homopolymer polypropylene, copolymer polypropylene,polyethylenes, polyethylene terephthalate, and the like. The container10 and preform 110 generally include the bodies 12,112 and a neck finish14 extending therefrom. The container 10 is generally hollow andcylindrical with a longitudinal axis that runs through closed lower ends16, 116 of the bodies 12, 112 and an open upper end 18 of the neckfinish 14. The container 10 is also generally symmetrical along itslongitudinal axis, with the exception of external threads 20 and adeflectable closure release 22 that are integrally formed on the neckfinish 14.

The closure release 22 is integrally connected to the container bycircumferentially spaced horizontal flexible and resilient arms 24 thatare integrally connected by a depressible bar 26. An open space isdefined between the depressible bar 26 and the neck finish 14 of thecontainers 10, 110, and a cantilevered lug 28 extends from a flexiblehinge portion 30 of the depressible bar 26 and terminates in an axialstop surface 32. The cantilevered lug 28 extends in a tangential,circumferential, or arcuate direction with respect to the outer diameterof the neck finish 14 and extends in the same direction as the directionof rotation of a closure member (not shown), which threads closed ontothe neck finish 14 of the container 10. The cantilevered lug 28 of theclosure release 22 ordinarily engages lugs (not shown) formed in theclosure member to resist removal of the closure member by a child,unless the depressible bar 26 of the closure release 22 is pressedradially inwardly and/or axially downwardly to pull the cantilevered lug28 downwardly and thereby disengage the axial stop surface 32 of thecantilevered lug 28 from the lugs of the closure.

The neck finish 14 and closure release 22 includes a positive stop toprevent over-deflection of the depressible bar 26. The positive stop isdefined by a pair of circumferentially spaced tab feet 34 (not shown inFIG. 2) and tab stops 36. The tab feet 34 extend longitudinally downwardfrom the bottom of the depressible bar 26. The tab stops 36 extendlongitudinally downwardly along the neck finish 14 from proximate thetop surfaces of the resilient arms 24. When the depressible bar 26 isdepressed, the cantilevered lug 28 gets deflected axially downwardly.However, if excessive force is used, then the tab feet 34 will engagethe tab stops 36 to prevent deflection of the closure release 22 furtherthan necessary to disengage the cantilevered lug 28. The release 22 issimilar to that on the child resistant container of U.S. Pat. No.6,039,195 (the '195 patent), which is incorporated by reference herein.

There are, however, several differences between the container 10 andpreform 110 of the present invention and the child resistant containerof the '195 patent. For example, the container 10 is an injection blowmolded article, whereas the container of the '195 patent is simplyinjection molded. The container preform 110 is a preformed article orparison, which is injection molded prior to being blow molded. Also, thecontainer 10 and preform 110 include a longitudinal parting line 40 anda transverse parting line 42 that intersect at the closure release 22.Finally, the container 10 and preform 110 include a smooth pad 44 (notshown in FIG. 2) on the neck finish 14 proximate the closure release 22,wherein the longitudinal parting line 40 is interrupted. Thisinterruption in the longitudinal parting line 40 will be explained infurther detail below in reference to the methods and apparatuses of thepresent invention.

Referring now to FIG. 4A, an injection molding apparatus 200 includes adie set generally defined by a lower die plate 210, an upper die plate212, and a die shaft 214 connected therebetween as is well known in theart. Various other well-known features, such as die springs, die pins,and the like are not shown for the sake of clarity and focus on thepresent invention. The injection molding apparatus 200 further includesa lower neck ring or finish block 216 and an upper neck ring or finishblock 218 fixedly mounted to the lower die plate 210 and upper die plate212 respectively, as is well-known in the art. In contrast, however, alower mold body 220 and an upper mold body 222 are slidably mounted tothe lower and upper die plates 210, 212 respectively. One or both of themold bodies 220, 222 include special axial features at forward ends 224,226 thereof, as will be discussed in further detail below. Likewise, oneor both of the finish blocks 216, 218 include complementary specialaxial features at rearward ends 228, 230 thereof, as will also bedescribed in detail below.

In any case, the mold bodies 220, 222 may be slidably, mounted in anymanner including using tongue and groove or dovetail features, mountingsecondary sliding subplates between the mold bodies and die plates,attaching pillow blocks and guide rails therebetween, any combination ofthe foregoing arrangements, or any other suitable sliding means.Similarly, a manifold block 232 and a mold nozzle 234 are slidablymounted to the lower die plate 220. Finally, a main nozzle 236 isfixedly mounted on the injection molding machine (not shown), as is wellknown in the art. The main nozzle 236 includes a nozzle body 238, aspring loaded nozzle 240, and a series of springs 242 therebetween, suchas Bellville washers, or the like. As is well known in the art ofinjection molding, a core pin (not shown) is generally provided betweenthe mold bodies 220, 222 and finish blocks 216, 218 to define theinterior of the preform container to be formed.

Referring to FIGS. 4A–4C, the apparatus operates according to thefollowing method. Die clamps (not shown) of the injection moldingmachine (not shown) apply transverse or downward pressure on the upperdie plate 212, as depicted by arrow C of FIG. 4A. This downward pressureurges the upper die plate 212 toward the lower die plate 210, therebyclosing together the upper and lower mold bodies 222, 220 and the upperand lower finish blocks 218, 216 as shown in FIG. 4B. Also, as depictedby arrow L in FIG. 4B, the mold bodies 220, 222 and the manifold block232 are advanced horizontally or longitudinally toward the finish blocks216, 218 such as by a pneumatic or hydraulic cylinder, rotary actuator,driving wedge, or the like (not shown). And, even though the nozzle body238 remains fixed, the spring loaded nozzle 240 stays in contact withthe manifold block 232 by virtue of the spring force applied by thesprings 242.

Accordingly, the mold bodies 220, 222 contact the finish blocks 216,218, as shown in FIG. 4C. The longitudinal parting line 40 of FIGS. 1–3is defined by the mating surface contact of the upper and lower moldbodies 222, 220 and the upper and lower finish blocks 218, 216. Next,clamp tonnage is applied to the upper die plate 212 by the injectionmolding machine, as depicted by arrow T in FIG. 4C. Molten plastic isthen injected through the main nozzle 236, manifold block 232, moldnozzle 234, and into the mold bodies 220, 222 and finish blocks 216, 218to form the preform container 110 of FIG. 3. Thereafter, the clamptonnage is released, the mold bodies 220, 222 are retractedlongitudinally back away from the finish blocks 216, 218, the die clampsrelease, and the upper die plate 212 returns to its home position asshown in FIG. 4A. Accordingly, the preform container 110 of FIG. 3 canthen be removed from the mold without distorting, flexing, or breakingthe closure release 22. Thereafter, the preform container 110 istransferred to a blow mold (not shown) where the body 112 of the preformcontainer 110 is blown to form the body 12 of the finished injectionblow molded container 10.

FIG. 5 is a partial cross-sectional view of the tooling apparatus 200 ofFIG. 4C that is taken along line 5—5. FIG. 5 illustrates the specialaxial features that were referred to above, and that are defined byspecific elements as will be discussed below. The axial features areprovided in the forward end 226 of the upper mold body 222 and in therearward end 230 of the upper finish mold 218, as briefly mentionedabove with respect to FIG. 4A. The axial features are also provided inthe lower mold body (not shown) and the lower finish block (not shown),which are not captured by the cross-section along lines 5—5.Nonetheless, reference will be made to the mold bodies 220, 222 and thefinish blocks 216, 218 even though only one each is shown in FIG. 5.

The axial features cooperate with one another to at least partially formportions of the closure release 22 of the container 10 and preform 110of FIGS. 1–3. Essentially, the axial features are defined by a moldingsurface or core 244 and a pocket 246. In the method described above,when the mold bodies 220, 222 are advanced longitudinally forward towardthe finish blocks 216, 218, the core 244 enters the pocket 246 to atleast partially define a cavity for forming the closure release 22 ofFIGS. 1–3. Also, the transverse parting line 42 of FIGS. 1–3 is definedby the mating surface contact of the forward ends 224, 226 of the moldbodies 220, 222 with the rearward ends 228, 230 of the finish blocks216, 218.

FIG. 5 depicts a portion of the preform 110 formed between a core pin248 and mold bodies 220, 222 and finish blocks 216, 218. The preform 110includes the tapered profile 138 (in the example shown), neck finish 14,depressible bar 26, and cantilevered lug 28.

FIG. 5 also shows the mold bodies 220, 222 having an external pilotsurface 250 of the core 244 that cooperates with an internal pilotsurface or the pocket 246 of the finish blocks 216, 218. The core 244includes a radially outward male feature 252, a radially inward malefeature 254, and central male feature 256 therebetween. Similarly, thecore 244 includes a radially outward female feature 258 for at leastpartially forming the depressible bar 26 of the containers of FIGS. 1–3,and the core 244 further includes a radially inward female feature 260for at least partially forming the cantilevered lug 28 of the containers10,110 of FIGS. 1–3. Likewise, the pocket 246 of the finish blocks 216,218 is further defined by a female feature 262 for at least partiallyforming the cantilevered lug 28. Accordingly, the core 244 cooperateswith the pocket 246 to define the closure release 22 and the spacesbetween the neck finish 14 and the closure release 22 of the container10 and preform 110 of FIGS. 1–3.

After the molten plastic is injected into the mold and the closurerelease member is formed, the mold bodies 220, 222 must axially retractsuch that the male features 252, 254, 256 axially clear the newly formedclosure release 22 and spaces, and such that the entire core 244 axiallyclears the pocket 246 of the finish blocks 216, 218. Only thereafter maythe mold bodies 220, 222 retract transversely with respect to thelongitudinal axis of the mold and preform container. Thus, the presentinvention enables efficient injection molding of a closure releasemember on an injection blow molded container.

FIGS. 6–7 are directed toward an apparatus 300 according to analternative embodiment of the present invention. FIG. 6 represents a topview of a finish block 310 and a mold body 312. The finish block 310includes recessed threads 314, 316 for forming the threads 20 on thecontainer 10 and preform 110 of FIGS. 1–3. The finish block 310 furtherincludes female features 318, 320 that partially define a cavity orpocket for partially forming the closure release 22 of the container 10and preform 110 of FIGS. 1–3.

Unlike the previously described embodiment, wherein the axial featuresare integrated into the mold bodies, this embodiment involvesincorporating a unique actuator assembly 318 into the mold body 312. Theactuator assembly 318 includes a cylinder 320 formed in a forward end322 of the mold body 312, into which a connected piston 324 and rod 326are disposed. A recessed retainer plate 328 is fastened over thecylinder 320 at the forward end 322 of the mold body 312 by fasteners330 such as screws, and the like. The retainer plate 328 seals thepiston 324 and rod 326 within the cylinder 320. A forward end 332 of therod 326 is fixed to a core 334. Essentially, the core 334 includes thesame or similar male and female features as the core 244 of FIG. 5,which features are not repeated in detail here. Nonetheless, the maleand female features (not shown) of the core 334, together with thepocket 319, 321 of the finish block 310, are provided for forming theclosure release 22 of the containers 10, 110 of FIGS. 1–3.

FIG. 7 illustrates a side view of a die plate 336 and the mold body 312of Fig. 6, wherein the piston 324, rod 326, and core 334 have beenadvanced from a home position, as in FIG. 6, into an advanced positionas shown here wherein the core 334 of the mold body 312 cooperates withthe pocket 319, 321 of the finish block 310 to form the closure release22 of the containers 10, 110 of FIGS. 1–3. The actuator assembly 318 maybe actuated to the advanced position by any manner wherein positivefluid pressure is supplied to a rearward side 338 of the piston 324 andmay be retracted or reversed by applying vacuum or a negative pressureto the rearward side 338 of the piston 324 or a positive pressure to aforward side 340 of the piston 324. Related equipment and features forthe actuator assembly 318 such as a pump, a fluid supply, and fluidpassages formed in the mold are well known in the art and, thus, are notshown here.

In general, a method is provided according to the present invention forinjection molding an article. A plurality of finish blocks is provided,wherein one or more of the plurality of finish blocks includes one ormore pockets. A plurality of mold bodies are provided, wherein one ormore of the plurality of mold bodies includes one or more core portionsthat cooperate with the pockets of the plurality of finish blocks. Thecore portion may be integrally formed in the plurality of mold bodies,as described above with respect to FIGS. 4A–5. The core portion may alsobe separately attached and actuated within the plurality of mold bodies,as described above with respect to FIGS. 6–7. Other alternative corearrangements are contemplated by, and well within the scope of, thepresent invention. The plurality of finish blocks are then closedtogether to form a neck-finish mold cavity and the plurality of moldbodies are closed together to form a body mold cavity. The core portionis advanced toward the plurality of finish blocks and cooperates withthe pocket to define a cavity for forming a radially extending elementof the article. The core portion is retracted from out of cooperationwith the pocket, before the mold bodies are separated from one another,thereby avoiding damage to the closure release of the article.

Persons of ordinary skill in the art will recognize that the abovedescription is intended to be illustrative of a couple presentlypreferred embodiments of the present invention, and not limitingthereof. Modifications and substitutions may be made without departingfrom the spirit and broad scope of the present invention as set forth inthe appended claims. For example, without limitation, the core has beenshown and described as either integrally formed in both upper and lowermold bodies or independently mounted within an upper mold body. But, thecore or portions thereof may be provided on more or less than two moldbodies. The above applies equally to the pocket within the finishblocks. Moreover, the mold bodies or core may traverse along directionsother than just parallel with the longitudinal axis of the mold. Also,the core may be provided on the finish blocks and the pocket provided inthe mold bodies. Likewise, the mold bodies may remain stationary, whilethe finish blocks and/or core are advanced with respect thereto. Othermodifications and variations will be apparent to skilled artisans inview of this disclosure, including the claims that follow.

1. A method of injection molding a plastic preform for subsequent blowmolding into a container, the plastic preform having a generallylongitudinal axis and a radially extending element, said methodcomprising the steps of: providing a plurality of finish blocks whereinat least one of said plurality of finish blocks includes a pocket thatpartially defines a cavity for said radially extending element of theplastic preform; closing said plurality of finish blocks together toform a neck-finish mold cavity; providing a plurality of mold bodieswherein at least one of said plurality of mold bodies includes a coreportion that partially defines said cavity for the radially extendingelement of the plastic preform; closing said plurality of mold bodiestogether to form a body mold cavity; with said finish blocks closed andsaid mold bodies closed, axially advancing at least said core portion ofsaid at least one of said plurality of mold bodies toward said pluralityof finish blocks, said core portion and said pocket cooperating todefine said cavity for the radially extending element; injecting amaterial into said body mold cavity, said neck-finish mold cavity andsaid cavity for the radially extending element; axially retracting saidat least said core portion away from said plurality of finish blocks;opening said plurality of finish bodies and said plurality of moldbodies, whereby the plastic preform may be removed from said pluralityof mold bodies without damage to the radially extending element; andproviding said core portion in a fixed position on at least one of saidplurality of mold bodies, wherein said step of advancing comprisesadvancing said plurality of mold bodies and said core portion in unison.